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Date: Wed, 13 Sep 2006 20:52:53 +0300 From: Al Boldi <a1426z@...ab.com> To: "John Stoffel" <john@...ffel.org> Cc: Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org Subject: Re: What's in linux-2.6-block.git John Stoffel wrote: > >>>>> "Al" == Al Boldi <a1426z@...ab.com> writes: > > Al> Jens Axboe wrote: > >> On Wed, Sep 13 2006, Al Boldi wrote: > >> > Jens Axboe wrote: > >> > > This lists the main features of the 'block' branch, which is bound > >> > > for Linus when 2.6.19 opens: > >> > > > >> > > - Splitting of request->flags into two parts: > >> > > - cmd type > >> > > - modified flags > >> > > Right now it's a bit of a mess, splitting this up invites a > >> > > cleaner usage and also enables us to implement generic "messages" > >> > > passed on the regular queue for the device. > >> > > > >> > > - Abstract out the request back merging and put it into the core io > >> > > scheduler layer. Cleans up all the io schedulers, and noop gets > >> > > merging for "free". > >> > > > >> > > - Abstract out the rbtree sorting. Gets rid of duplicated code in > >> > > as/cfq/deadline. > >> > > > >> > > - General shrinkage of the request structure. > >> > > > >> > > - Killing dynamic rq private structures in deadline/as/cfq. This > >> > > should speed up the io path somewhat, as we avoid allocating > >> > > several structures (struct request + scheduler private request) for > >> > > each io request. > >> > > > >> > > - meta data io logging for blktrace. > >> > > > >> > > - CFQ improvements. > >> > > > >> > > - Make the block layer configurable through Kconfig (David > >> > > Howells). > >> > > > >> > > - Lots of cleanups. > >> > > >> > Does it also address the strange "max_sectors_kb<>192 causes a > >> > 50%-slowdown" problem? > >> > >> (remember to cc me/others when replying, I can easily miss lkml > >> messages for several days otherwise). > >> > >> It does not, the investigation of that is still pending I'm afraid. The > >> data is really puzzling, I'm inclined to think it's drive related. Are > >> you reproducing it just one box/drive, or on several? > > Al> Several boxes, same drive. > > Al> /dev/hda: > > Al> ATA device, with non-removable media > Al> Model Number: WDC WD1200JB-00DUA0 > Al> Serial Number: WD-WMACM1007651 > Al> Firmware Revision: 65.13G65 > Al> Standards: > Al> Supported: 6 5 4 3 > Al> Likely used: 6 > > I've got a pair of drives which are very close in model type, and I > can run some non-destructive tests on them if you like to confirm > what's going on here if you like: > > /dev/hde: > > ATA device, with non-removable media > Model Number: WDC WD1200JB-00CRA1 > Serial Number: WD-WMA8C4365875 > Firmware Revision: 17.07W17 > Standards: > Supported: 5 4 3 > Likely used: 6 > jfsnew:~> sudo hdparm -I /dev/hdg | head > > /dev/hdg: > > ATA device, with non-removable media > Model Number: WDC WD1200JB-00EVA0 > Serial Number: WD-WMAEK2844058 > Firmware Revision: 15.05R15 > Standards: > Supported: 6 5 4 > Likely used: 6 > > The drives have different defaul max_sectors too: > > cat /sys/block/hdg/queue/max_sectors_kb > > 512 > > > cat /sys/block/hde/queue/max_sectors_kb > > 128 > > Let me know your test method and I'll run it here and post the > results. Thanks for your input! Are you running UDMA5? Can you dump the full hdparm -I What thruput do you get with cat /dev/hd[eg] > /dev/null? What does cat /sys/block/hde/queue/read_ahead_kb say? Then try this for best performance: echo 192 > /sys/block/hde/queue/max_sectors_kb echo 192 > /sys/block/hde/queue/read_ahead_kb and repeat the thruput test reporting vmstat results. Thanks! -- Al - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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